73 360 Ignition timing after Chain replacement
Should I be worried my Cam timing is off? (Chain installed tooth off?) Or time it to feel, listen for pinging under load and adjust accordingly?
No, on the first and
yes on the second.
But
First put all-new fresh gas in the tank, and drive it, If it still has problems getting down to a TRUE 2.5*; AND if you installed the original Holley 2-bbl; get rid of that trouble maker. The low speed circuit in that carb is nearly impossible to get right, it will take you hours and days. The simplest is to just get rid of it.
Here's the deal;
I ran the Mopar 292/292/108 cam, in from 4* retarded to 8* advanced and it idled just fine at from 5* advanced to 18* advance in any of those cam-timed positions. And with a Holley 4-bbl , after the tune was in, it took throttle like a champion.
So what you say.
So I don't care where your cam-timing is. IMO, for your application, if it starts and runs at 15*, the cam-timing is close enough.
Why it won't idle at 5* is a whole nuther problem. And I agree with everyone who says to go out and get a piston stop and PROVE your TDC mark! A dowel in the whole means absolutely nothing no matter how careful you think you are being. At TDC your 360 has a window of crank rotation, of at least 5*, where the piston just about dwells, with almost no piston movement. That's problem #1. And saying it looks the same as another one laying on the bench, is just as vague and means nothing.That's problem #2.
Problem #3, is that you haven't said a word about your Power-Timing so I assume you don't know it. And this is almost critical to know, far more critical than your Idle Timing. Lets say your mechanical advance system is set up for 2.5* advance at idle. That means the factoryD for that engine would have been designed for it and would probably bring the PowerTiming to at least 32* at some unknown by me higher rpm, guessing 3600. That means the centrifugal would be about 30 Degrees. Now, if you set the Idle Timing to 15, and the D brings in another 30, that totals 45, which is enough to rattle all your piston skirts straight into the oilpan. That's problem #3.
Problem #4 is we don't know your elevation, nor at what temperature your engine was running when it stalled, These are key things to know.
So you gotta fix these problems before you do anything.
However this does not prevent you from doing some other diagnostics as to why it won't idle with short timing. And my guess is,either;
1) the carb is not fueling correctly, or
2) the engine is getting too much air from an unregulated source, or
3) the valves are not sealing.
I suggest you start by making sure all the vacuum accessories are properly hooked up and functioning correctly, including especially the PCV system,and the brake booster; and if everything is; then
do a LeakDown test
Why?
If the valves are not sealing, the vacuum will be low. To compensate for this; You will either increase the throttle opening, or increase the timing, or perhaps both. But in either case the throttle blades will not be in the right place as regards the transfer slots.
So if you try to run at say 5*, you will have to increase the throttle opening, but the engine will not get enough fuel, so you will likely max out the mixture screws in an attempt to keep her running, or you will end up with a high idle.
But, at 15* you can reduce the throttle opening, and the Idle-vacuum will be higher, so now the carb is working "better". But the fact is still, that the manifold vacuum is too low in the first place due to the valves not sealing.
Without doing a LD test, you can chase yurazz around for hours because you don't know that the vacuum is or what it should be.
A compression test could be done, but has to be interpreted by the numbers and the environment. Saying "good" means exactly nothing to me. Your "good" is gonna be different from my "good" which is gonna be different than somebody else's "good" . Furthermore, this test gas to be done properly, which means;
disable the coil, wire the throttle at WOT, ALL plugs out, and with a fully charged battery, crank it as many compression cycles as it takes to get two consecutive same/near-same readings. Whether it be 5 or 12 cycles, just crank it.
But these numbers do not, by themselves, prove your valves are sealing.
They just give a general view of the condition of your engine. See, you said you put in new bearings, but you never mentioned rings nor boring nor honing, or what the ring gaps were, so the compression numbers would be somewhat meaningless, especially not knowing your elevation; Oregon is not Kansas.
